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22 Cards in this Set
- Front
- Back
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What is the purpose of electrocardiography?
5 major reasons |
2. To evaluate chest pain, shortness of breath, dizziness, or heart palpitations
2. To detect an abnormality in the heart's rate or rhythm (dysrhythmia) 3. To detect the presence of impaired blood flow to the heart muscle (cardiac ischemia) 4. To help diagnose damage to the heart caused by a myocardial infarction 5. Determine the presence of hypertrophy of the heart |
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Trace the path blood takes through the heart, starting with the right atrium.
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R atrium
R ventricle pulmonary artery lungs (picks up oxygen) pulmonary veins L atrium L ventricle (most muscular & powerful chamber of the heart) aorta throughout body |
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What is the function of the coronary arteries?
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Supply the heart with oxygen and nutrients.
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What is the function of the SA node?
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It initiates and regulates the heartbeat
(pacemaker of the heart) |
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Why is the impulse initiated by the SA node delayed momentarily by the AV node?
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To allow for complete contraction of the atria and filling of the ventricles with blood from the atria.
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What is the cardiac cycle?
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Represents one complete heartbeat. Consists of the contraction of the atria, the contraction of the ventricles, and the relaxation of the entire heart.
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P wave
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represents the electrical activity associated with the contraction of the atria (atrial depolarization)
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QRS complex
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represents the electrical activity associated with contractions of the ventricles (ventricular depolarization)
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T wave
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represents electrical recovery of the ventricles (ventricular repolarization)
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P-R segment
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time interval from the end of the atrial depolarization to the beginning of the ventricular depolarization
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S-T segment
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time interval from the end of the ventricular depolarization to the beginning of repolarization of the ventricles
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P-R interval
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time interval from beginning of the atrial depolarization to the beginning of the ventricular depolarization
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Q-T interval
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time interval from beginning of the ventricular depolarization to the end of repolarization of the ventricles.
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Why is the R wave taller than the P wave on the ECG graph cycle?
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The ventricles are larger than the atria, therefore they require a stronger electrical stimulus to depolarize the ventricles.
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Why does atrial repolarization not appear as a separate wave on the ECG cycle?
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It occurs at the same time as ventricular depolarization [QRS complex], so it is masked, or hidden, by the QRS complex
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Why is the baseline flat following the U wave?
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Because the heart is at rest or polarized and no electrical activity is occuring in the heart, so there is nothing to record.
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What changes can occur on an ECG due to coronary artery disease?
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a depressed S-T segment and an inverted T wave
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What changes can occur on an ECG due to myocardial infarction?
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a larger than normal Q wave and an elevated S-T segment
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What is the purpose of standardizing the electrocardiograph?
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This calibration is a quality control measure that ensures an accurate and reliable recording. It also means an ECG run on one machine compares in accuracy with an ECG run on another machine.
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How high should the standardization mark be when the electrocardiograph is standardized?
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10 mm
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What is a lead, and what information does it provide?
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A tracing of the electrical activity of the heart between 2 electrodes. Each lead provides an electrical "photograph" of the heart's activity from a different angle.
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What is the function of an electrode?
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Used to record a resting 12-lead electrocardiogram
A good conductor of electricity Picks up and records influence |
